Tuesday, May 29, 2007

20 Minutes of Secondhand Smoke Exposure Puts You at Risk of Stroke, Says Anti-Smoking Group

According to a statement by Smokefree Air for Everyone (Columbia, MO) published in the Columbia Business Times, being exposed to secondhand smoke for just 20 minutes puts you at risk of having a stroke due to the formation of blood clots:

"After 20 minutes, blood platelets look like a pack-a-day smoker’s, making your blood “sticky” and contributing to stroke causing blood clots."The Rest of the Story

I consider this statement to be inaccurate, and I think it might unnecessarily scare people into thinking that if they are exposed to secondhand smoke for just 20 minutes, they might develop a blood clot and suffer a stroke.

The good news is that the statement is not accurate. If you are an otherwise healthy person -- or in fact, even if you are unhealthy but as long as you do not have severe pre-existing cerebrovascular disease (atherosclerosis of the arteries supplying the brain), you are not at risk of suffering a stroke from 20 minutes of secondhand smoke exposure.

While it is true that chronic exposure to secondhand smoke can cause atherosclerosis and put an individual at increased risk of a stroke, a mere 20 minutes of exposure cannot cause a stroke in anyone who does not already have severe cerebrovascular disease and who is already basically a stroke waiting to happen.

In other words, if someone has cerebrovascular disease that is so severe that any temporary increase in platelet activation may be enough to trigger life-threatening clot formation, then that individual is at severe risk of suffering a stroke, from secondhand smoke exposure, eating a high-fat meal (which can also activate platelets), or any of a large number of other exposures.

The important point here is that the claim is not qualified as applying only to people with extremely severe, pre-existing cerebrovascular disease. The way I read the statement, it is applying to anyone. After all, it states that 20 minutes of secondhand smoke makes "your" blood sticky, putting you at increased risk of a stroke. Thus, it seems intended to apply to any reader, meaning that it is a general statement of increased risk for the entire exposed public.

While I agree wholeheartedly with the goals of the SAFE coalition and support the Columbia smoke-free workplace law, I am uncomfortable with the idea of using exaggerated, misleading, and fallacious health claims in order to support those goals and that law.

I think the actual effects of secondhand smoke are enough; we do not need to go beyond the truth in order to promote our policy goals.

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About Me

Dr. Siegel is a Professor in the Department of Community Health Sciences, Boston University School of Public Health. He has 32 years of experience in the field of tobacco control. He previously spent two years working at the Office on Smoking and Health at CDC, where he conducted research on secondhand smoke and cigarette advertising. He has published nearly 70 papers related to tobacco. He testified in the landmark Engle lawsuit against the tobacco companies, which resulted in an unprecedented $145 billion verdict against the industry. He teaches social and behavioral sciences, mass communication and public health, and public health advocacy in the Masters of Public Health program.